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Shouldn't Dawkins now say that Darwinian evolution has been refuted?

If there were a heaven in which all the animals who ever lived could frolic, we would find an interbreeding continuum between every species and every other. For example I could interbreed with a female who could interbreed with a male who could . . . fill in a few gaps, probably not very many in this case . . . who could interbreed with a chimpanzee. We could construct longer, but still unbroken chains of interbreeding individuals to connect a human with a warthog, a kangaroo, a catfish. This is not a matter of speculative conjecture; it necessarily follows from the fact of evolution.

And I'm putting it together with this recent announcement: Animal/human cybrids aren't working. They don't produce embryos. What this means in practice is that (to some scientists' dismay) animal eggs cannot be used to fix the human egg shortage for all those cloned embryos they want for research. Aw, shucks.

Oh, they were never planning to stop that. They just weren't getting as much as they wanted that way. Hence the idea of cybrids.

I just find it amusing that Dawkins was so extravagant: "necessarily follows from the fact" is strong language. Scientists shouldn't even talk that way. You have to add a dickens of a lot of auxiliaries to _any_ scientific theory to get something to "necessarily follow" from it. So he went out on quite a limb. Now they discover they get useless junk when they try to combine human DNA with animal eggs in cloning-type experiments (as a friend of mine predicted, I might add), and the crickets are chirping over what should be, *given Dawkins's statement*, a rather shocking announcement.

I guess I oughtta give him a break. He only said all this interbreeding would be possible if we were in a heaven containing all the animals who ever lived. So that gives him an out. However, he did go on in the rest of the post to fantasize about experiments that would prove evolution, including human-animal hybrids. The possibility is certainly much more to be expected given the truth of Darwinism than given its falsehood.

Yet even greater stuff that all the more profoundly demonstrates the magnificent depravity of the modern man.

Perhaps they'll finally justify passing a proposition that would ultimately allow for bestiality (and, further, the attending civil rights concerning rightful marriage between both man and beast) as even Dawkins' rather abysmal conception of heaven would have it: the beatific vision has just been superbly relegated to the 'bestial' vision!

Dawkins said "all the animals that ever lived", not "all animals that are currently alive". He was making a theoretical point about the genetic continuity of life, not an absurd claim that all different living species can interbreed.

That's why I said maybe I should give him a break. However, if you read the rest of the column, you'll find that he fantasizes about experiments to demonstrate evolution, including _present-day_ hybrids. He says he feels a "frisson" of excitement (sort of like Matthews's thrill, I guess) at contemplating them. Clearly he regards such hybrids as predicted far more strongly by Darwinian evolution than by its negation, and I think that this is in fact correct: Darwinian evolution predicts such hybrids more strongly than its negation, though it does not predict the possibility of hybrids among currently existing species in an absolute sense (that is, with a very high probability). The apparent physical impossibility of such hybrids is some evidence against Darwinism as Dawkins conceives it.

Dawkins said "all the animals that ever lived", not "all animals that are currently alive". He was making a theoretical point about the genetic continuity of life, not an absurd claim that all different living species can interbreed.

Am I missing something? If the statement is true for all animals that ever lived, then it's also necessarily true for all animals that are currently alive, since "all animals that are currently alive" is a subset of the group of "all animals that ever lived." Not that I want to put too fine of a distinction on another absurd statement by Dawkins, king of the blundering blowhards.

I gather the idea is that nowadays our subset contains species which may have diverged "too far" from their common ancestry to interbreed, but that if only we had _all_ the species that had ever lived, why then...Nonetheless, as I said, Dawkins makes it clear in the rest of the article that he has some real hope and expectation of hybridization possibilities with present-day species--even with humans and apes, for that matter.

I gather the idea is that nowadays our subset contains species which may have diverged "too far" from their common ancestry to interbreed, but that if only we had _all_ the species that had ever lived, why then...

Ah, yes. All of the transitional species that would make this demonstration simple have all conveniently disappeared. But if evolution is happening all the time (it didn't stop or anything, did it?) then there should be lots of species that are closely related enough to make the demonstration simple it seems to me. I know you're not defending his argument. I just don't think stillnotking's appeal to "all animals who ever lived" as opposed to "all animals currently alive" is much of a defense. And as you pointed out Dawkins's conclusion does seem to follow if evolution is true.

Anybody ever watch the remake of "The Fly?" (on the subject of hybridization). Now that's a disgusting film.

Accepting falsification has never been one of the strong points of someone who takes Dawkins's position. If someone in that position is canny, he'll go on about how we shouldn't be Popperians and about how we don't believe in falsification anymore and so forth. Dawkins went pretty far out on a limb in that post, though. His only loophole is the "all the animals who ever lived" line. And given the other things he said in the post, it isn't much of a loophole.

Being merely a vessel for carting around genes, I can't even say my genes, still a spontaneous, non-necessitarian twitch prompts me to suggest that the Larmarckian thesis may have some life out there in what will be undoubtedly described as the fringes of pseudo-science.

If so, and if it survives the scorn of those who would never describe themselves as The Establishment, what twists and turns, what wondrous mental gymnastics, what acrobatics of rhetoric and evasion will occur in those hollowed halls & present themselves for observation to those uninitiated to the inner sanctums of the religion of science.

And how long will Mr. Dawkins have to be strapped down in his bed, not that he will be alone in his torment.

However, if you read the rest of the column, you'll find that he fantasizes about experiments to demonstrate evolution, including _present-day_ hybrids. He says he feels a "frisson" of excitement (sort of like Matthews's thrill, I guess) at contemplating them.

And he says that he doubts such hybrids are possible. There's also the fact that Dawkins is talking about chimpanzees, and the second article you linked is referring to livestock. Your ridiculous allusion to Chris Matthews gives the whole game away, Lydia: you are not making a good-faith argument that Darwinian evolution has been falsified. You are indulging in partisan distortion of the views of a person you happen not to like. Doubtless this exercise carries some psychological payoff for you, but that's all.

Darwinian evolution predicts such hybrids more strongly than its negation, though it does not predict the possibility of hybrids among currently existing species in an absolute sense (that is, with a very high probability). The apparent physical impossibility of such hybrids is some evidence against Darwinism as Dawkins conceives it.

No. The apparent impossibility of creating human/chicken embryonic cybrids is not "evidence against Darwinism". It's evidence against some cartoon version of Darwinism to which no biologist, in Darwin's time or since, would subscribe.

Sorry, buddy. If the occurrence of human-animal hybrids would be evidence for Darwinism (which Dawkins implies that it would--using the phrase "a practical demonstration"), its non-occurrence and indeed apparent impossibility is of necessity evidence against. As it turns out, the strength of the evidence for and the evidence against needn't be the same. In fact, the strength of the evidence in the two different directions can be radically different. That's an oddity of probability theory. But if some evidence E is evidence for some hypothesis H and against ~H, then ~E is, *to some degree*, evidence for ~H and against H.

I suppose you could try to say that human-chicken cybrids would _not_ be evidence for Darwinism, that only human-chimp cybrids would be. But I would point out that Dawkins apparently thinks the creation of human-mouse chimeras with approximately 50-50 cells from each would be another "practical demonstration," so there is no reason to think he is _restricting_ his evidential claims to human-chimp crosses. And I think there can be no doubt whatsoever that if the cybrid experiments attempted and to which I linked _had_ been successful, this would have been considered (by Dawkins along with others) as evidence for Darwinism. The rest follows as a matter of simple probability theory, with the qualification I have already given regarding the relative strengths of the cases, which need not be the same.

I don't know what you mean by claiming that Dawkins says that he doubts such hybrids are possible. Here is the quotation:

A successful hybridization between a human and a chimpanzee. Even if the hybrid were infertile like a mule, the shock waves that would be sent through society would be salutary. This is why a distinguished biologist described this possibility as the most immoral scientific experiment he could imagine: it would change everything! It cannot be ruled out as impossible, but it would be surprising.

How the goalposts have moved: first the cybrid experiments called for an admission from Richard Dawkins that Darwinian evolution has been "refuted". Now they are merely evidence "to some degree", however slight and trivial, against Darwinism. It's human nature to want to salvage something from the ruins of an argument, but unfortunately there is no salvage here. The cybrid experiments were not conducted to prove or disprove the most basic theory in evolutionary biology, i.e. that organisms share common descent*. If they had been, the experimenters would have used close relatives of human beings, such as... chimpanzees! Now you see why Dawkins brought up chimpanzees rather than chickens. If Dawkins thinks that even a successful human/chimp hybrid would be "surprising", what does this imply about the prospects of chicken-people?

*Note that Dawkins is not attempting to prove or disprove this theory either. He makes it clear that common descent is scientifically proven beyond a reasonable doubt. When he says a human-chimp hybrid would "change everything", he is talking the popular perception of human beings as ontologically distinct from animals. The entire premise of your argument is therefore false: Dawkins never claimed nor meant that viable human-animal hybrids would buttress the scientific theory of evolution.

No, he says a "practical demonstration." Sorry, but that means "strong evidence for" on any ordinary construction. And mice are not considered, AFAIK, to be particularly close evolutionary relatives of humans, certainly not as close as chimps. And please, let's not pretend that Dawkins & co. would not have considered the attempted cybrids to be evidence for their theory.

Dawkins never claimed nor meant that viable human-animal hybrids would buttress the scientific theory of evolution.

No, but he strongly suggested that they should be possible as a necessary consequence of evolution. Thus, if it turns out experimentally that they aren't possible (which is what the evidence seems to suggest at this point) then that certainly would have to count against the theory. So I'm not really sure what you're quibbling about. You seem to have missed the point altogether.

Not that evolution is really falsifiable anyways, as Lydia said in her comment about the rejection of Popperianism by Darwinists. It's just the new orthodoxy. So Dawkins says thinking of humans as distinct from animals is "un-evolutionary" in the same way that we Christians use the term "unbiblical." It's a little bizarre.

When he says a human-chimp hybrid would "change everything", he is talking the popular perception of human beings as ontologically distinct from animals.

What an odd position to hold. A dead human body and a living human being are made of the same stuff, yet they are still ontologically distinct. There is a greater ontological distinction between a dead human body and a living human being than between a living human being and a living chimp, or even between a living human being and a living flower.

"What kind of stuff this thing is made of" has a part to play in ontology, but certainly not as big a part as Prof. Dawkins - at least according to you - would believe it to play. But I suppose such a thing is to be expect when natural historians play at being metaphysicians.

No, but he strongly suggested that they should be possible as a necessary consequence of evolution. Thus, if it turns out experimentally that they aren't possible (which is what the evidence seems to suggest at this point) then that certainly would have to count against the theory. So I'm not really sure what you're quibbling about. You seem to have missed the point altogether.

I didn't miss the point, I refuted it. Dawkins did not claim that successful human-animal hybrids would be evidence for evolution. Nothing in his article was written from the standpoint of seeking proof or disproof of common descent. Lydia is the one who erroneously read it that way. I have no idea what you mean when you say he "strongly suggested" it, and I suspect you don't either.

Not that evolution is really falsifiable anyways, as Lydia said in her comment about the rejection of Popperianism by Darwinists. It's just the new orthodoxy. So Dawkins says thinking of humans as distinct from animals is "un-evolutionary" in the same way that we Christians use the term "unbiblical." It's a little bizarre.

Nonsense. I can think of any number of experimental results that would disprove common descent. Fossil rabbits in the Precambrian is the classic example -- one that Richard Dawkins explicitly agreed with, by the way, no tea-leaf reading or "strong suggestions" required. Experimental evidence that genotype has nothing to do with phenotype or that the genomes of all living species are relationally equidistant would also refute the theory at a stroke.

No tea-leaf reading at all. "Practical demonstration" is a pretty strong term. Obviously the reason Dawkins suggests that any or all of the things he lists would be so shaking to the world (and esp. to those people he so despises who view man and other animals as crucially distinct) is _because_ they would be, he implies, so conclusive on issues like common Darwinian descent. The column makes no sense on any other interpretation.

But if it turned out (if anyone ever tried it) that chimp eggs also did not reprogram human DNA in SCNT, would that mean anything to you, SNK? They are unlikely to try it for many reasons, one of which is that it would be difficult to obtain chimp eggs.

No, he says a "practical demonstration." Sorry, but that means "strong evidence for" on any ordinary construction. And mice are not considered, AFAIK, to be particularly close evolutionary relatives of humans, certainly not as close as chimps. And please, let's not pretend that Dawkins & co. would not have considered the attempted cybrids to be evidence for their theory.

Really? So when my high school physics teacher gave the class a practical demonstration of Newton's First Law, he was trying to prove it?

Let's pretend that the theory of common descent is already established to the satisfaction of every working biologist, including the biologists who worked on the hybrid experiments. Let's pretend that the only people who think that unviability of a cybrid between humans and livestock would "refute" the theory of common descent are cranks. Under that pretend scenario, does Dawkins' article make a little more sense?

Your first comment was that Dawkins didn't make the claim "that all different living species can interbreed." That's true, but nobody here said he did. Then in your next post you claimed that "he says that he doubts such hybrids are possible." That's false, at least in the context of the article. All he said is that "I have not said that I hope any of them [his four scenarios] will be realised." But that's a much different claim than saying that he doubts they're possible. Talk about shifting the goalposts!

Now you've decided to take aim at a third target, saying that "Dawkins did not claim that successful human-animal hybrids would be evidence for evolution." True, but irrelevant. If they should be possible as a necessary consequence of evolution then the fact that they aren't possible has to count against the theory. That's just the way science works. It may not work that way for Dawkins, because he's not looking to confirm or falsify evolution for himself. He's a true believer. He's just hoping for some kind of demonstration that will convince the masses out of their "un-evolutionary" thinking that humans are distinct from animals. I don't think he'll have much luck, since humans so obviously are distinct from animals. Only a true believer could blind himself to such an obvious fact.

So when my high school physics teacher gave the class a practical demonstration of Newton's First Law, he was trying to prove it?

This is just a maddeningly bogus statement. When your teacher gave said demonstration he was demonstrating something that had been demonstrated thousands of times before. Have human/chimp cybrids been demonstrated thousands of times already? Perhaps you could give the date and location and forward to Dawkins. Apparently he's out of the loop.

This is just a maddeningly bogus statement. When your teacher gave said demonstration he was demonstrating something that had been demonstrated thousands of times before. Have human/chimp cybrids been demonstrated thousands of times already? Perhaps you could give the date and location and forward to Dawkins. Apparently he's out of the loop.
Brother.

Sorry you're so upset, but I think you misinterpreted me as well as Dawkins. My point is simply that the phrase "practical demonstration" is not synonymous with "scientific proof". The scientific proof of the theory of common descent has already been accomplished. Practical demonstrations are always nice as teaching tools, but Dawkins manifestly was not staking the theory on them, much as you and Lydia wish it were so.

By the way, you somewhat lower the force of your accusations of bogusness when you have already claimed that the theory of evolution is "unfalsifiable" and that currently living species should be able to interbreed because they are a "subset" of all species that have ever lived. To put it charitably, I think your bogus-meter is a little off.

By the way, you somewhat lower the force of your accusations of bogusness when you have already claimed that the theory of evolution is "unfalsifiable" and that currently living species should be able to interbreed because they are a "subset" of all species that have ever lived.

I didn't claim that any currently living species should be able to interbreed at all. In fact I never even said that any non-living species should be able to interbreed. That's what Dawkins said. Try to pay attention, will you? My point was that if something is true for all species that ever lived then it should also be true for all species currently alive. Lydia pointed out the caveat that it has to do with the supposed evolutionary distance between currently living species, though if evolution is still happening then there should still be some species closely related enough to demonstrate the thing.

You can claim evolution is falsifiable all you want. I don't believe for even a second that Dawkins would abandon evolution if pre-Cambrian rabbits were discovered. They'd just invent another just-so story to cover for that just like they have with the Cambrian explosion and other evidence that goes against the theory.

Dawkins manifestly was not staking the theory on them, much as you and Lydia wish it were so.

I never said Dawkins was staking the theory on them, and I'm pretty sure Lydia didn't either. In fact I specifically denied it when I said, "It may not work that way for Dawkins, because he's not looking to confirm or falsify evolution for himself. He's a true believer."

The question isn't whether Dawkins thinks the theory depends on it. It's whether the theory actually depends on it. You just keep arguing about what Dawkins thinks. Lydia's point was about what's true in fact. She didn't say "Dawkins thinks that being unable to make hybrids would falsify evolution." She just says the implication of what Dawkins said is that it would, regardless of whether Dawkins thinks it would or not. Do you follow me yet?

I'd like to direct your attention to the title of the post for assistance in divining what Lydia's point was. If she believes that the failure of animal/human cybrids constitutes a refutation of the theory of common descent, she should say that. Heck, maybe even publish it -- fame and fortune await the scholar who overturns the foundations of our understanding of biology! Instead she preferred to focus on rubbing Dawkins' nose in what she erroneously perceived as a misstep on his part; petty stuff, really, but she doesn't seem inclined to let it go, even after reluctantly conceding its unfairness.

She just says the implication of what Dawkins said is that it would, regardless of whether Dawkins thinks it would or not.

Really -- so Lydia understands what Dawkins said better than Dawkins himself understood it? And here I thought the godless liberal scientists were supposed to be the arrogant ones.

You and she are simply wrong. Dawkins was not saying what you think he was saying. The plain meaning of his column is evident without searching for "strong suggestions" or other artful dodges. He said, paraphrasing, that we already know there is a theoretical breeding continuum of all species that have ever lived, but that many people do not fully understand this, so it would be nice if we could produce actual human/chimp hybrids as a practical demonstration of the concept. (This is analogous to an astronomer wishing for a practical way to view distant galaxies, or a physicist wishing for a practical way to observe subatomic particles.) Whether or not such a practical demonstration exists is irrelevant to the truth of the theory, which has already been confirmed and reconfirmed in countless other ways.

Believe it or not, the pictures of the galaxies and the viewing of the subatomic particles would indeed be evidence for their existence. That is true even if we already had strong independent evidence of their existence. It's not like evidence stops being evidence once we already have other evidence. This should be fairly obvious.

And here's the heart of the matter, really: Dawkins most definitely never said the theory of common descent predicts that even human/chimp hybrids should be viable, much less human/X hybrids. Dodge and twist and impute "strong suggestions" to the man all you like, he never said that. Therefore the entire premise of Lydia's post is incorrect, and she should have the honesty to admit it and move on.

Believe it or not, the pictures of the galaxies and the viewing of the subatomic particles would indeed be evidence for their existence. That is true even if we already had strong independent evidence of their existence. It's not like evidence stops being evidence once we already have other evidence. This should be fairly obvious.

Yep, and what should also be fairly obvious is that if it turns out to be technically impossible to take such pictures, this is not evidence against the existence of the galaxies or particles.

"Technically impossible to take" admits of several different interpretations. If people started telling us that such-and-such a hypothetical galaxy isn't the type of thing one can take a picture of, then we should start having suspicions that something odd is going on.

He said, paraphrasing, that we already know there is a theoretical breeding continuum of all species that have ever lived, but that many people do not fully understand this, so it would be nice if we could produce actual human/chimp hybrids as a practical demonstration of the concept.

Gee, that's funny. Aren't you the same the guy who said that Dawkins "says that he doubts such hybrids are possible"? Maybe you better get Dawkins on the phone to straighten his story out. It's funny for someone to get a "frission of enjoyment" out of contemplating things that he thinks aren't possible.

Yes, John, I knew what you meant; we all misspell words occasionally. But that's still one of the most tiresome and feeble attempts at a "gotcha" I've ever seen, even eclipsing Lydia's original post in its (deliberate?) obtuseness. IOW spelling is the least of your problems.

Go ahead. Let's see you reconcile those two statements with something a little more substantive than hand-waving about me being obtuse. Or I could just point out the fact that Dawkins never said that he doubts hybrids are possible and that was just a blunder on your part. How's that for a "gotcha"?

I doubt I'll win the lottery, but I still get excited thinking about it. How's that?

Not bad. But it doesn't change the fact that Dawkins didn't say he doubts hybrids are possible.

I'd say the honest answer to both questions is clearly "no", which means Lydia's post had no purpose whatsoever. Anyone want to answer "yes" to either question and defend their reasoning?

If the answer to #1 is clearly "no" then I don't really understand what Dawkins was going on about. Why even talk about it in that case? If it doesn't follow from the theory then how would creating actual hybrids do anything to give a demonstration of evolution?

"Creating hybrids would be a great practical demonstration of evolution and 'change everything', except that being able to make hybrids doesn't follow from the theory." I'm afraid I can't make any sense of something like. Perhaps you can explain how I'm being obtuse.

I don't know about you, but I'm not often surprised by things I expect.

Why even talk about it in that case? If it doesn't follow from the theory then how would creating actual hybrids do anything to give a demonstration of evolution?

This just doesn't seem that complicated to me. Dawkins was laying out some fanciful "what-if?" scenarios that he felt would transform the popular view of human essentialism by a concrete, practical demonstration of its falsehood. (I think he was being rather naively optimistic myself: human essentialism will last as long as humans do.) He could have written the same article but wished for a time machine instead of the four possible events he mentioned, but presumably he'd rather focus on things that seem at least vaguely possible.

Dawkins was laying out some fanciful "what-if?" scenarios that he felt would transform the popular view of human essentialism by a concrete, practical demonstration of its falsehood.

Are you trying to say that the "practical demonstration" in question is something other than a practical demonstration of common descent? That's a nonsensical interpretation. The practical demonstration of the falsehood of "essentialism" which Dawkins says is "un-evolutionary" is based on the truth of evoution, particularly of common descent. So demonstrating the falsehood of essentialism is done by demonstrating the truth of common descent. There's no other viable interpretation of Dawkins's words.

Going back to your illustration of a practical demonstration of Newton's First Law, the only way anything can be a practical demonstration of a theory is if it follows from that theory. You can't say that creating hybrids is a good practical demonstration of common descent if it doesn't follow from the theory. You also can't have it both ways: if it works we'll say it's a good practical demonstration of the theory; if it doesn't work, we'll say it doesn't follow from the theory. Either it follows from the theory (in which case it is indeed a practical demonstration of the theory) or it doesn't (in which case it can't be a practical demonstration). I think you're trying to have your cake and eat it, too.

Btw, in point of actual fact, prediction should be regarded as comparative rather than being required to be absolute. There is no question at all that Darwinism predicts hybridization possibilities, even among existing species, comparatively more strongly than does its negation. Indeed, I rather doubt that most Darwinists, including Dawkins, would deny this.

Nope. You're just holding Dawkins to a silly and unreasonable standard -- you're trying to make this an argument about something that it's not about.

Let me try one more time. Let's turn this around. I believe you mentioned earlier that you're a Christian. Say a Christian writer wrote an article like Dawkins', but on the theme of Christianity rather than common descent -- for example, if he fantasized about the discovery of a secret code in the Gospels that predicted, in clear and comprehensible language, the major events of human history from the birth of Christ onward. "That would be great," this hypothetical writer says, "because it would show everyone that the Bible truly is the Word of God." Now, does this writer think it's likely that such a code will be discovered? Probably not. Does the truth of Christianity depend on the discovery of such a code? Of course not. Would it be fair for atheists to claim that the failure of Bible scholars to discover this putative code constitutes evidence against the truth of the Gospels, under this author's standards? No way.

In other words, if I encountered such an article, I might shake my head at the folly of the writer, but I wouldn't write a post like Lydia's to call him out about it. Because that would be pointless, and unfair.

Btw, in point of actual fact, prediction should be regarded as comparative rather than being required to be absolute. There is no question at all that Darwinism predicts hybridization possibilities, even among existing species, comparatively more strongly than does its negation. Indeed, I rather doubt that most Darwinists, including Dawkins, would deny this.

Interesting that you should say this, because quite a few viable (if infertile) interspecies hybrids do exist, of course. Does that make Darwinism more likely than its negation?

Because "P implies Q" doesn't mean "not-P implies not-Q". The existence of viable human/X cybrids would imply the truth of common descent, but their impossibility doesn't imply its falsehood. The existence of the Secret Gospel Code would imply the truth of Christianity, but the nonexistence of that code doesn't imply Christianity's falsehood.

Correct. This is the fallacy of denying the antecedent. But that's not what's going on here.

Some phenomenon is predicted by the theory. We'll call the theory P and the phenomenon Q (just to make it really confusing). So then: if P then Q means that if the theory is true then the phenomenon Q will follow from it. If the phenomenon does not obtain (~Q) then what you actually have is Modus Tollens: If P then Q. ~Q therefore ~P.

If P (if the theory is true) then Q (the phenomenon will obtain). ~Q (the phenomenon does NOT obtain) therefore ~P (the theory is not true).

SNK - just for the record, I'd really like to thank you for contributing here, per my challenge to you over at the FORVM.

All too often, defenders of the "theory of common descent" simply treat doubters - and especially Christian doubters - as fools or knaves, undeserving of even the minimal respect necessary to give them a serious listen and a serious reply. I think that approach is deeply counter-productive, and I thank you (again) for moving beyond it.

That is exactly correct, John, but you've reversed the P's and Q's as I was using them -- I was referring to the phenomenon as P and the theory as Q. So, adopting your formulation of P for the theory (common descent) and Q as the phenomenon (human/animal cybrids):

P implies Q: FALSE (common descent does not imply viable human/animal cybrids -- as discussed & stipulated above, it only implies a breeding continuum between all animals that have ever lived, not all animals that are currently alive)
Q implies P: TRUE (a viable human/animal cybrid would imply the truth of common descent)
not-P implies not-Q: TRUE (no common descent implies no human/animal cybrids)
not-Q implies not-P: FALSE (no human/animal cybrids does not imply no common descent)

Any arguments with that truth table? Let's see how it breaks down for my Gospel example.

Yep, looks about right. I think we're finally down to brass tacks here. Someone who believes in a P could certainly wish for a Q to prove it, without in any way committing himself to not-Q implying not-P.

SNK - just for the record, I'd really like to thank you for contributing here, per my challenge to you over at the FORVM.

All too often, defenders of the "theory of common descent" simply treat doubters - and especially Christian doubters - as fools or knaves, undeserving of even the minimal respect necessary to give them a serious listen and a serious reply. I think that approach is deeply counter-productive, and I thank you (again) for moving beyond it.

I always enjoy these discussions, and while I've met plenty of fools and knaves online, I don't see any in this thread. I was having a bad day earlier and did indulge in a little ad hom, for which I'd like to apologize to Lydia and John -- it's not my custom.

Someone who believes in a P could certainly wish for a Q to prove it, without in any way committing himself to not-Q implying not-P.

Err, should be obvious, but I confused myself here -- reverse the P's and Q's in that sentence. Someone can believe in a Q and hope for a P to demonstrate it to the world (because P implies Q), without fearing not-P implying not-Q.

These things should be dealt with probabilistically rather than deductively.

I actually would never fantasize about a secret code like that, btw. I think it would be an exceedingly silly thing and has no particular strength at all for supporting Christianity.

If H predicts E more strongly than does ~H, then ~E is at least some evidence for ~H. Part of the difficulty here is that E is actually a composite, involving many different hybridization possibilities. For example, as SNK points out, there are some infertile hybrids. However, there appear to be major big-time limits to hybridization possibilities, as these recent experiments show. I don't actually think Dawkins is fully clear on all of that, and I think he is indeed going out on a limb in the post. My own opinion would be, off the cuff, that the major limits on hybridization are notably stronger evidence against the full-scale Darwinian story than the few hybridization possibilities are evidence for it.

Err, should be obvious, but I confused myself here -- reverse the P's and Q's in that sentence. Someone can believe in a Q and hope for a P to demonstrate it to the world (because P implies Q), without fearing not-P implying not-Q.

Um, never mind. This post was the confused one. The original post was correct as written. Long day, think I'll go to bed now... I'll come back tomorrow.

we have a problem for Ev. Simply put, by the theorem on total probability,

P(Cyb) = P(Ev)P(Cyb|Ev) + P(~Ev)P(Cyb|~Ev)

So if P(Cyb) is, say, less than or equal to 0.01, this puts very severe upper bounds on P(Ev) -- no matter what (coherent) value one plugs in for P(Cyb|~Ev). Given the constraints above, P(Ev) is, at a maximum, barely larger than 0.01. (Strictly, it is bounded by 0.01/P(Cyb|Ev).)

There are two ways out here: to withdraw the claim that P(Cyb|Ev) is close to 1, or to deny that the article Lydia has cited really does indicate that P(Cyb) is close to 0. But under those constraints, Dawkins has a problem.

Isn't this the claim that SNK is challenging, though? I agree that this is what it looks like Dawkins is saying, but that's the issue under dispute. I was looking for a good killer argument to show that this is what's implied by Dawkins's remarks. I thought I had it, but then next thing I know I'm drowning in a sea of symbolic logic (and something looks a little fishy in there!).

I leave it to the reader to decide for himself if Dawkins got carried away and wrote carelessly. I think the Dawkins post is pretty clear: He doesn't think the hybridization and chimera ideas are overwhelmingly far-fetched and indeed, the people he would expect to be particularly surprised by them would be precisely those "essentialists" whose views are "deeply un-evolutionary." That's why he thinks it would be exciting if they happened.

This doesn't require tea leaves. It's there throughout the entire piece, which was pretty obviously tossed off without a lot of thought. Here's just one more bit of evidence, and at that point I leave it to the reader to read the whole thing through and see if it is at all compatible with, "It's enormously scientifically unlikely, on my evolutionary theory, that animal-human hybrids of existing beings are even physiologically possible."

The quotation above about the heaven with the frolicking animals is immediately preceded by, "But such 'essentialism' is deeply un-evolutionary." And still more notably, it is immediately followed by, "Theoretically we understand this. But what would change everything is a practical demonstration, such as one of the following:" The "this" that would merely be "practically demonstrated" by (inter alia) interspecies hybridization in the here and now is precisely the statement quoted in the main post about an interbreeding heaven in which all creatures that ever lived could frolic.

Well, it looks like the thread's just about done, but I'm not quite ready to pack it in. I'm still a little muddled by SNK's "truth table".

Is it not the case that some phenomenon can only serve as a demonstration of a theory if that phenomenon follows at least with high probability on the theory (or that Pr(phe|th) is close to 1 as Tim has shown in his analysis)? This seems like an interesting question to me which is why I'm still working on it here. If you wanted to demonstrate Newton's first law by putting a bucket of water on a skateboard, pushing the skateboard, and watching the water spill on the floor, that only works because the probability of the water spilling is very close to 1 given Newton's first law. You wouldn't say that the probability of Newton's first law being true is close to 1 given the water spilling. The water could still spill if Newton's first law is wrong. But if Newton's first law is right the water has to spill (or has a very high probability of spilling). So while the probability of the water spilling is high given Newton's first law (which is what makes it a good demonstration), we don't have a good way of calculating the probability of Newton's first law given the water spilling. It's working backwards, almost like the fallacy of affirming the consequent. If the water doesn't spill, Newton's first law is in trouble.

So with the hybrid/cybrid deal, it's a good demonstration only if the probability of cybrids is high given evolution. But we can't calculate the probability of evolution given cybrids. Cybrids could still be possible even if evolution is false. Science works from a theory which is proposed to explain some set of data and then the theory is demonstrated by saying "if the theory is true then some phenomenon X will probably follow."

Maybe I'm over-thinking this one, but it does strike me as interesting and somewhat important to get right.

Is it not the case that some phenomenon can only serve as a demonstration of a theory if that phenomenon follows at least with high probability on the theory (or that Pr(phe|th) is close to 1 as Tim has shown in his analysis)?

Everything that Tim said was correct, but that doesn't follow from it, unless by "demonstration" you mean "something that was predicted ahead of time." That would be one normal meaning of "demonstration" and still more of "practical demonstration," and that's why careful supporters of a theory don't talk like Dawkins talked. I would never sit around saying, "We Christians all believe theoretically that God is all-powerful and all-good, but in our hearts we don't really believe it. What would be great is some practical demonstration to refute the unbiblical thinking of people like Richard Dawkins, like God's curing so-and-so from cancer right now." It would be reckless and stupid and would cause understandable confusion when so-and-so wasn't cured. Some event can serve as strong _evidence_ of a theory even if its probability on all theories is quite low, so long as the Bayes factor gives it a _proportionally_ much higher probability on H than on ~H. This is why smart people explain the evidence they actually have rather than fantasizing about making "practical demonstrations" to the ignorant masses to silence them.

unless by "demonstration" you mean "something that was predicted ahead of time." That would be one normal meaning of "demonstration" and still more of "practical demonstration," and that's why careful supporters of a theory don't talk like Dawkins talked.

I think this is where a large part of the confusion is coming from. This is how I meant demonstration - something that actually follows from the theory. Although in the case of cybrids we're talking about something that hasn't been demonstrated yet and looks to be improbable based on previous attempts. But if Dawkins isn't making a prediction, then I can't make any sense of what he is saying.

It's like with SNK's Bible code illustration. It's not just the case that a Bible code doesn't follow from the truth of Christianity, it's also the case that the truth of Christianity wouldn't follow from the existence of a Bible code. In fact, this has been done. Some guy claimed to have discovered a Bible code some years ago that predicted future events (causing quite a stir), and somebody else who thought it was legit suggested that this proved the Bible was written by space aliens using supercomputers and a time machine (I'm not making this up!). So you were right to say that the hypothetical code would be a silly thing with no supportive value for Christianity. At the same time, it's probably true that a lot of people would find such evidence compelling. But this would only serve to show that most people don't understand proper logical relations and not that the truth of Christianity followed in any way from a Bible code or was even made more probable by a Bible code.

Accepting falsification has never been one of the strong points of someone who takes Dawkins's position. If someone in that position is canny, he'll go on about how we shouldn't be Popperians and about how we don't believe in falsification anymore and so forth.

Also Lydia:

These things should be dealt with probabilistically rather than deductively.

These two statements are incoherent. One cannot champion Popperian falsification theory and then shift into probabilistic inductive reasoning without revealing a fundamental unseriousness. I think it should be clear at this point that what Dawkins wrote does not "refute" the theory of common descent under his own terms. Establishing that demolishes the original argument of the post.

If we now wish to discuss the probability of common descent being correct, I'm game, but of course that is a much wider discussion than a single column by Richard Dawkins, and our probabilistic calculus will need to include a great many more terms. We would, for example, discuss the existence of interspecies hybrids, the reams of genetic information on living species and the degree to which it confirms previously constructed phylogenetic trees, the universality of DNA/RNA transcription processes, and the fossil record. Of course, to do this would be to recapitulate much of the scientific literature of the past hundred and fifty years or so.

Just wanted to point out that the Dawkins article and the animal-cell hybrid article are talking about two very different things.

The animal-cell hybrid article is referring to the inability of other animals' eggs to reset human nuclei to a ground state. Researchers were hoping that the contents of the eggs, which include mitochondria and multiple chemical and enzyme gradients responsible for kick-starting development and front/back and top/bottom asymmetries, were identical enough to those of human eggs that they could be used to make "reset" stem cells as another alternative to using enucleated human eggs or human embryos.

This is an indication that egg environments have probably evolved too much. They're not giving up, though. This tells them that the eggs are different; the next step will be to tell by how much. Chances are that those, too, will follow a typical tree-of-life pattern.

Dawkins' chimeras and the like are a different beast. Already-developed cells can live together, and it's not quite the same gradient issue, though there are probably still some developmental chemical differences that could cause chimera failure.

The key to your question is to disentangle two separate questions about evidence: (1) whether a bit of evidence E renders a hypothesis H very probable, and (2) whether E does some heavy lifting on behalf of the odds on H. In the former case, we get something of the form P(H|E) > k, where k is some number close to 1, e.g., .95. In the latter case, we have P(H|E) > P(H), but there's no general guarantee of a specific P(H|E).

Think of this latter conception in terms of the odds form of Bayes's Theorem:

P(H|E)/P(~H|E) = P(H)/P(~H) x P(E|H)/P(E|~H)

If the ratio of the likelihoods, on the far right, is very top heavy, say by 10 to 1 or 100 to 1, then that shifts the ratio of the posterior probabilities (far left) by that factor vis a vis the ratio of the prior probabilities (immediately to the right of the equals sign). To use Swinburne's terminology, E provides a strong C-inductive argument for H; it confirms (whence Swinburne's 'C') H strongly. But because the ratio of the prior probabilities may be bottom-heavy, this information does not, by itself, suffice to tell us that P(H|E) exceeds any given value k.

If we take the second notion as our account of evidence, then it is not necessary for P(E|H) to be close to 1. It may in fact be quite small, provided that P(E|~H) is smaller. So, to illustrate, let P(E|H) = .01 and P(E|~H) = .0001. Then the ratio of the likelihoods is 100 to 1, and E provides a substantial boost to the odds on H -- despite the fact that there is only a 1% probability of E, given that H.

To move from odds to probabilities, just remember that odds of A to B on H yield a probability for H of A/(A + B). So odds of 100 to 1 translate to a probability of 100/101, or a bit over .99.

There are some good reasons for taking the likelihood ratio as a measure of the degree of confirmation that E gives to H. But that takes us into some technical issues that are probably out of place in a combox.

Some guy claimed to have discovered a Bible code some years ago that predicted future events (causing quite a stir), and somebody else who thought it was legit suggested that this proved the Bible was written by space aliens using supercomputers and a time machine (I'm not making this up!).

Now you know how I feel about people who disbelieve the theory of common descent. :)

Lydia wasn't championing Popperian falsificationism; she was pointing out that it's a hard position for a Dawkinsian to hold onto. Anyone familiar with Lydia's technical papers knows that she is a thoroughgoing probabilist.

FWIW, I think it is perfectly reasonable to believe in common descent, and I do myself, though even that is far from the conclusively proven case that Dawkins et al pretend it to be. "Man is descended from bacteria" is doubtless as true a statement as "Ruby is descended from machine language"; but what that doesn't imply is in many ways far more interesting than what it does imply.

On the other hand I think the neodarwinian synthesis - random mutation and selection as explanation of the transition from prokaryote world to our present state - is conclusively refuted by the evidence. Random polypeptide chains don't fold into a stable native state at all, let alone into a nontoxic stable native state, let alone into a beneficial stable native state which gives selection something to work with. Neo-darwinian evolution is only good for minor tweaks and for the elimination of unnecessary traits, or for turning preexisting traits on and off: it is useless as an engine for building wholly new proteins, cell types, tissues, organs, and species.

Separate still is the question of how the first prokaryotes came about, for which there is no scientific explanation at all, merely speculation: how we went from not having DNA polymerase to having a not only nontoxic but beneficial process of translation, itself built and sustained by the very process of translation which it implements, is completely unknown, and likely unknowable.

We really have no scientific idea how prokaryote world became the modern world, other than wild speculations. People like Dawkins pretend that we do for ideological and religious reasons, period.

Only if by "help" you mean "make your head explode". But I appreciate the attempt! In just 15 minutes of intense concentration I think I have a vague idea of what you're saying. So I think I can work through that comment over the next week or two, and I'm sure I'll be better for it. It does remind me of my single biggest regret in life: not having taken more classes from you when I had the chance.

But that takes us into some technical issues that are probably out of place in a combox.

I know you didn't intend it this way, but I found that statement to be more than a little ironic! I'm officially bowing out of this thread to let my brain recover for awhile (plus we're traveling this weekend).

Dear Lydia and John Fraser and the rest of the head-nodders and "yeah!" sayers in this thread,

stillnotking is right and you are all wrong. Sorry, but clearly none of you, save stillnotking, even knows what evolution by natural selection and speciation is.

One of the tests used in biology to decide if something is a new species, is the fact that it cannot reproduce with its closely related, seemingly similar cousins. Or they produce sterile offspring, as an indication they are on their way.

You seem to have misread or purposely misrepresented what Dawkins said, quote mined it out of context, in order to set up this absurd strawman.

I guess when the facts are not on your side, all you have is dishonesty, right?

Let me help: go to youtube and watch the videos by DonExodus2 (a Christian, I might add), like this series:

When you have learned something, I hope you realize how ridiculous you statements are. if you are still not convinced, I hope you learn how and what needs to be disproven so you can have an intelligent discussion and not sound like morons.

I know it probably should give rise to my chivalrous instinct to smite the impudent; but what in fact happens when a commenter attacks Lydia's knowledge, intelligence, and education is that it makes me laugh out loud. Why not just tattoo "Look at me, I'm an ignorant doofus" to your forehead?

Again, my point is that Dawkins's post was rhetorically smart-alecky and reckless. Does he have retreat positions he can take now, loopholes and wiggle-room in the most rigidly strained and favorable interpretation of his exact words? Yes, he does. Was it silly for him to say what he did say? Yes, it was. I think his post speaks for itself. Nobody who thought hybrids among existing creatures _wildly implausible_ and indeed _biologically impossible_ would be likely to write the way that he does in that post. It was a dumb way to write. He was trying to be "edgy" and "provocative," but that sort of thing has a way of back-firing. Naturally, his supporters won't want to grant this. In fact, even though SNK above said that if researchers were trying to "prove or disprove" neo-Darwinian common descent they would have used chimps to try to create a hybrid. Yet I would be willing to bet that if it were tried and there appeared to be strong in-principle biological blocks to it, just as there appear to be with mice, rabbits, and cows, SNK wouldn't abate an iota of his own support for Darwinism, despite his having said that. That's the way it goes.

I do not, indeed, champion Popperian falsification. And neither does any canny Darwinist. But for that very reason I counsel them not to sit about fantasizing about practical demonstrations and experiments to silence us stupid human essentialists once and for all.

This is so trivially easy to understand that I'm having a hard time believing that obviously intelligent people supposedly don't.

If you could travel back in time several hundred million years (at least), to the point where life moved from exclusively self-replicating, to sexually reproducing organisms, it would obviously be possible (given that common descent is one of the most well supported theories in science) to witness the development of new species (it is almost certain that you would not notice that what we class as a new species today had arisen, possibly until thousands of generations later).

As each new species arose, it would be possible to witness an interbreeding continuum, with species only separated by the distance to their last common ancestor. Think of it this way: each and every one of us can trace our ancestry back in time. There is a continuum between ourselves and our great, great, great, great, great, great, etc, etc, Grandmother and Grandfather. That is, in essence, Dawkins very simply point.

The oldest fossil evidence of anatomically modern humans is 130,000 years ago. There are more than 20 fossil hominids (all of which have gone extinct, apart from us) which appear in the fossil record through more than 2 million years, all the way back to australopithecines, and back further to both our own, as well as the chimpanzee's, last common ancestor (note: it was almost certainly not a linear progression). This continuum can theoretically be traced back to the beginning of, at the very least, the first sexually reproducing organisms.

Dawkins is emphatically not suggesting that humans should be able to mate with a "mouse, cow and rabbit" (as per the article in question). How on earth anyone could conclude as such is quite honestly staggering.

And in any case, the falsification of common descent says absolutely nothing about the other aspects of "Darwinian" evolution (in particular, natural selection as a mechanism), and it most certainly wouldn't falsify the modern evolutionary synthesis (apart from, obviously, common descent!).

By the way, in case anyone wishes to argue with fossil evidence, it has been said that, even if we hadn't found a single fossil, the genetic evidence is so overwhelmingly powerful, it would make not one jot of a difference (well, perhaps a few paleontologists and anthropologists might be out of a job).

Feel free to re-read my comment from 12:32 if you really require further clarification as to my point. I say more or less the same thing elsewhere in the thread, and I think my earlier example regarding a preacher suggesting a "practical demonstration" of the goodness and power of God (to shock people who don't really fully believe in God's goodness and power in their hearts) in the healing of so-and-so's cancer is also helpful. One might consider what would happen if a preacher actually did say that and the person died of cancer shortly thereafter. While the preacher could say, truly enough, that he didn't outright predict that the person would be healed, the rhetorical situation would be pretty awkward for him.

Aren't we, though? I propose that the "idea" that humans are special will be rather difficult to "break down" considering it's so obviously true, to expert and laymen alike. Those who speak the greatest evidence for human uniqueness are the ones who argue so vociferously against it.

One might consider what would happen if a preacher actually did say that [so-and-so's cancer would be healed] and the person died of cancer shortly thereafter. While the preacher could say, truly enough, that he didn't outright predict that the person would be healed, the rhetorical situation would be pretty awkward for him.

It's happened many times, and the rhetorical solution is that either the patient didn't believe strongly enough or that god had "a reason for calling him home" that we will someday understand once we are in the divine presence.

I mean, of course, among those who are not already believers. They would, of course, scoff. And they would be unimpressed by the preacher's statement that he didn't actually predict the cure, even though that statement would be technically correct. I also note that "evolution has reasons we don't understand" is not even a possible explanation for the naturalist.

I also note that "evolution has reasons we don't understand" is not even a possible explanation for the naturalist.

Precisely my point. "God has reasons we don't understand" is always the out for believers when things do not go the way they "should." On the other hand, science is the process of discovering why things that "shouldn't" happen do happen. The major forward leaps in science rarely begin with someone shouting "Eureka!" The most common verbal precursor to a major scientific breakthrough is "That's funny . . ."

[T]hey would be unimpressed by the preacher's statement that he didn't actually predict the cure, even though that statement would be technically correct.

This post is a paradigm case of intellectual dishonesty, even for Lydia's standards. Shame on you! People like you give analytic philosophy and probability theory a bad name. And You don't do theism or essentialism any good; it's easy for Dawkins and his followers to dismiss your farcical objections. Bravo for stillnotking.

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